Related to #626
When authentication expires after some time, users see "Connection lost"
and must refresh the page to see "Authentication required". This commit
implements automatic redirect to login when authentication expires.
Changes:
- Add authentication check to WebSocket endpoint to prevent unauthenticated
WebSocket connections
- Handle WebSocket close with code 1008 (policy violation) as auth failure
and redirect to login
- Intercept 401 responses on API calls (except initial auth checks) and
automatically redirect to login page
- Clear stored credentials and set logout flag before redirect to ensure
clean login flow
This provides a better user experience by immediately redirecting to the
login page when the session expires, rather than showing a confusing
"Connection lost" message that requires manual page refresh.